/**
 * @file
 * User Datagram Protocol module\n
 * The code for the User Datagram Protocol UDP & UDPLite (RFC 3828).\n
 * See also @ref udp_raw
 *
 * @defgroup udp_raw UDP
 * @ingroup callbackstyle_api
 * User Datagram Protocol module\n
 * @see @ref raw_api and @ref netconn
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */

/* @todo Check the use of '(struct udp_pcb).chksum_len_rx'!
 */

#include "lwip/opt.h"

#if LWIP_UDP /* don't build if not configured for use in lwipopts.h */

#include "lwip/udp.h"
#include "lwip/def.h"
#include "lwip/memp.h"
#include "lwip/inet_chksum.h"
#include "lwip/ip_addr.h"
#include "lwip/ip6.h"
#include "lwip/ip6_addr.h"
#include "lwip/netif.h"
#include "lwip/icmp.h"
#include "lwip/icmp6.h"
#include "lwip/stats.h"
#include "lwip/snmp.h"
#include "lwip/dhcp.h"

#include <string.h>

#ifndef UDP_LOCAL_PORT_RANGE_START
	/* From http://www.iana.org/assignments/port-numbers:
	"The Dynamic and/or Private Ports are those from 49152 through 65535" */
	#define UDP_LOCAL_PORT_RANGE_START  0xc000
	#define UDP_LOCAL_PORT_RANGE_END    0xffff
	#define UDP_ENSURE_LOCAL_PORT_RANGE(port) ((u16_t)(((port) & ~UDP_LOCAL_PORT_RANGE_START) + UDP_LOCAL_PORT_RANGE_START))
#endif

/* last local UDP port */
static u16_t udp_port = UDP_LOCAL_PORT_RANGE_START;

/* The list of UDP PCBs */
/* exported in udp.h (was static) */
struct udp_pcb* udp_pcbs;

/**
 * Initialize this module.
 */
void
udp_init(void)
{
#if LWIP_RANDOMIZE_INITIAL_LOCAL_PORTS && defined(LWIP_RAND)
	udp_port = UDP_ENSURE_LOCAL_PORT_RANGE(LWIP_RAND());
#endif /* LWIP_RANDOMIZE_INITIAL_LOCAL_PORTS && defined(LWIP_RAND) */
}

/**
 * Allocate a new local UDP port.
 *
 * @return a new (free) local UDP port number
 */
static u16_t
udp_new_port(void)
{
	u16_t n = 0;
	struct udp_pcb* pcb;

again:

	if(udp_port++ == UDP_LOCAL_PORT_RANGE_END) {
		udp_port = UDP_LOCAL_PORT_RANGE_START;
	}

	/* Check all PCBs. */
	for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
		if(pcb->local_port == udp_port) {
			if(++n > (UDP_LOCAL_PORT_RANGE_END - UDP_LOCAL_PORT_RANGE_START)) {
				return 0;
			}

			goto again;
		}
	}

	return udp_port;
}

/** Common code to see if the current input packet matches the pcb
 * (current input packet is accessed via ip(4/6)_current_* macros)
 *
 * @param pcb pcb to check
 * @param inp network interface on which the datagram was received (only used for IPv4)
 * @param broadcast 1 if his is an IPv4 broadcast (global or subnet-only), 0 otherwise (only used for IPv4)
 * @return 1 on match, 0 otherwise
 */
static u8_t
udp_input_local_match(struct udp_pcb* pcb, struct netif* inp, u8_t broadcast)
{
	LWIP_UNUSED_ARG(inp);       /* in IPv6 only case */
	LWIP_UNUSED_ARG(broadcast); /* in IPv6 only case */

	/* Dual-stack: PCBs listening to any IP type also listen to any IP address */
	if(IP_IS_ANY_TYPE_VAL(pcb->local_ip)) {
#if LWIP_IPV4 && IP_SOF_BROADCAST_RECV

		if((broadcast != 0) && !ip_get_option(pcb, SOF_BROADCAST)) {
			return 0;
		}

#endif /* LWIP_IPV4 && IP_SOF_BROADCAST_RECV */
		return 1;
	}

	/* Only need to check PCB if incoming IP version matches PCB IP version */
	if(IP_ADDR_PCB_VERSION_MATCH_EXACT(pcb, ip_current_dest_addr())) {
#if LWIP_IPV4

		/* Special case: IPv4 broadcast: all or broadcasts in my subnet
		 * Note: broadcast variable can only be 1 if it is an IPv4 broadcast */
		if(broadcast != 0) {
#if IP_SOF_BROADCAST_RECV

			if(ip_get_option(pcb, SOF_BROADCAST))
#endif /* IP_SOF_BROADCAST_RECV */
			{
				if(ip4_addr_isany(ip_2_ip4(&pcb->local_ip)) ||
				        ((ip4_current_dest_addr()->addr == IPADDR_BROADCAST)) ||
				        ip4_addr_netcmp(ip_2_ip4(&pcb->local_ip), ip4_current_dest_addr(), netif_ip4_netmask(inp))) {
					return 1;
				}
			}
		} else
#endif /* LWIP_IPV4 */

			/* Handle IPv4 and IPv6: all or exact match */
			if(ip_addr_isany(&pcb->local_ip) || ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr())) {
				return 1;
			}
	}

	return 0;
}

/**
 * Process an incoming UDP datagram.
 *
 * Given an incoming UDP datagram (as a chain of pbufs) this function
 * finds a corresponding UDP PCB and hands over the pbuf to the pcbs
 * recv function. If no pcb is found or the datagram is incorrect, the
 * pbuf is freed.
 *
 * @param p pbuf to be demultiplexed to a UDP PCB (p->payload pointing to the UDP header)
 * @param inp network interface on which the datagram was received.
 *
 */
void
udp_input(struct pbuf* p, struct netif* inp)
{
	struct udp_hdr* udphdr;
	struct udp_pcb* pcb, *prev;
	struct udp_pcb* uncon_pcb;
	u16_t src, dest;
	u8_t broadcast;
	u8_t for_us = 0;

	LWIP_UNUSED_ARG(inp);

	PERF_START;

	UDP_STATS_INC(udp.recv);

	/* Check minimum length (UDP header) */
	if(p->len < UDP_HLEN) {
		/* drop short packets */
		LWIP_DEBUGF(UDP_DEBUG,
		            ("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
		UDP_STATS_INC(udp.lenerr);
		UDP_STATS_INC(udp.drop);
		MIB2_STATS_INC(mib2.udpinerrors);
		pbuf_free(p);
		goto end;
	}

	udphdr = (struct udp_hdr*)p->payload;

	/* is broadcast packet ? */
	broadcast = ip_addr_isbroadcast(ip_current_dest_addr(), ip_current_netif());

	LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));

	/* convert src and dest ports to host byte order */
	src = lwip_ntohs(udphdr->src);
	dest = lwip_ntohs(udphdr->dest);

	udp_debug_print(udphdr);

	/* print the UDP source and destination */
	LWIP_DEBUGF(UDP_DEBUG, ("udp ("));
	ip_addr_debug_print(UDP_DEBUG, ip_current_dest_addr());
	LWIP_DEBUGF(UDP_DEBUG, (", %"U16_F") <-- (", lwip_ntohs(udphdr->dest)));
	ip_addr_debug_print(UDP_DEBUG, ip_current_src_addr());
	LWIP_DEBUGF(UDP_DEBUG, (", %"U16_F")\n", lwip_ntohs(udphdr->src)));

	pcb = NULL;
	prev = NULL;
	uncon_pcb = NULL;

	/* Iterate through the UDP pcb list for a matching pcb.
	 * 'Perfect match' pcbs (connected to the remote port & ip address) are
	 * preferred. If no perfect match is found, the first unconnected pcb that
	 * matches the local port and ip address gets the datagram. */
	for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
		/* print the PCB local and remote address */
		LWIP_DEBUGF(UDP_DEBUG, ("pcb ("));
		ip_addr_debug_print(UDP_DEBUG, &pcb->local_ip);
		LWIP_DEBUGF(UDP_DEBUG, (", %"U16_F") <-- (", pcb->local_port));
		ip_addr_debug_print(UDP_DEBUG, &pcb->remote_ip);
		LWIP_DEBUGF(UDP_DEBUG, (", %"U16_F")\n", pcb->remote_port));

		/* compare PCB local addr+port to UDP destination addr+port */
		if((pcb->local_port == dest) &&
		        (udp_input_local_match(pcb, inp, broadcast) != 0)) {
			if(((pcb->flags & UDP_FLAGS_CONNECTED) == 0) &&
			        ((uncon_pcb == NULL)
#if SO_REUSE
			         /* prefer specific IPs over cath-all */
			         || !ip_addr_isany(&pcb->local_ip)
#endif /* SO_REUSE */
			        )) {
				/* the first unconnected matching PCB */
				uncon_pcb = pcb;
			}

			/* compare PCB remote addr+port to UDP source addr+port */
			if((pcb->remote_port == src) &&
			        (ip_addr_isany_val(pcb->remote_ip) ||
			         ip_addr_cmp(&pcb->remote_ip, ip_current_src_addr()))) {
				/* the first fully matching PCB */
				if(prev != NULL) {
					/* move the pcb to the front of udp_pcbs so that is
					   found faster next time */
					prev->next = pcb->next;
					pcb->next = udp_pcbs;
					udp_pcbs = pcb;
				} else {
					UDP_STATS_INC(udp.cachehit);
				}

				break;
			}
		}

		prev = pcb;
	}

	/* no fully matching pcb found? then look for an unconnected pcb */
	if(pcb == NULL) {
		pcb = uncon_pcb;
	}

	/* Check checksum if this is a match or if it was directed at us. */
	if(pcb != NULL) {
		for_us = 1;
	} else {
#if LWIP_IPV6

		if(ip_current_is_v6()) {
			for_us = netif_get_ip6_addr_match(inp, ip6_current_dest_addr()) >= 0;
		}

#endif /* LWIP_IPV6 */
#if LWIP_IPV4

		if(!ip_current_is_v6()) {
			for_us = ip4_addr_cmp(netif_ip4_addr(inp), ip4_current_dest_addr());
		}

#endif /* LWIP_IPV4 */
	}

	if(for_us) {
		LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
#if CHECKSUM_CHECK_UDP
		IF__NETIF_CHECKSUM_ENABLED(inp, CHECKSUM_CHECK_UDP) {
#if LWIP_UDPLITE

			if(ip_current_header_proto() == IP_PROTO_UDPLITE) {
				/* Do the UDP Lite checksum */
				u16_t chklen = lwip_ntohs(udphdr->len);

				if(chklen < sizeof(struct udp_hdr)) {
					if(chklen == 0) {
						/* For UDP-Lite, checksum length of 0 means checksum
						   over the complete packet (See RFC 3828 chap. 3.1) */
						chklen = p->tot_len;
					} else {
						/* At least the UDP-Lite header must be covered by the
						   checksum! (Again, see RFC 3828 chap. 3.1) */
						goto chkerr;
					}
				}

				if(ip_chksum_pseudo_partial(p, IP_PROTO_UDPLITE,
				                            p->tot_len, chklen,
				                            ip_current_src_addr(), ip_current_dest_addr()) != 0) {
					goto chkerr;
				}
			} else
#endif /* LWIP_UDPLITE */
			{
				if(udphdr->chksum != 0) {
					if(ip_chksum_pseudo(p, IP_PROTO_UDP, p->tot_len,
					                    ip_current_src_addr(),
					                    ip_current_dest_addr()) != 0) {
						goto chkerr;
					}
				}
			}
		}
#endif /* CHECKSUM_CHECK_UDP */

		if(pbuf_header(p, -UDP_HLEN)) {
			/* Can we cope with this failing? Just assert for now */
			LWIP_ASSERT("pbuf_header failed\n", 0);
			UDP_STATS_INC(udp.drop);
			MIB2_STATS_INC(mib2.udpinerrors);
			pbuf_free(p);
			goto end;
		}

		if(pcb != NULL) {
			MIB2_STATS_INC(mib2.udpindatagrams);
#if SO_REUSE && SO_REUSE_RXTOALL

			if(ip_get_option(pcb, SOF_REUSEADDR) &&
			        (broadcast || ip_addr_ismulticast(ip_current_dest_addr()))) {
				/* pass broadcast- or multicast packets to all multicast pcbs
				   if SOF_REUSEADDR is set on the first match */
				struct udp_pcb* mpcb;
				u8_t p_header_changed = 0;
				s16_t hdrs_len = (s16_t)(ip_current_header_tot_len() + UDP_HLEN);

				for(mpcb = udp_pcbs; mpcb != NULL; mpcb = mpcb->next) {
					if(mpcb != pcb) {
						/* compare PCB local addr+port to UDP destination addr+port */
						if((mpcb->local_port == dest) &&
						        (udp_input_local_match(mpcb, inp, broadcast) != 0)) {
							/* pass a copy of the packet to all local matches */
							if(mpcb->recv != NULL) {
								struct pbuf* q;

								/* for that, move payload to IP header again */
								if(p_header_changed == 0) {
									pbuf_header_force(p, hdrs_len);
									p_header_changed = 1;
								}

								q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);

								if(q != NULL) {
									err_t err = pbuf_copy(q, p);

									if(err == ERR_OK) {
										/* move payload to UDP data */
										pbuf_header(q, -hdrs_len);
										mpcb->recv(mpcb->recv_arg, mpcb, q, ip_current_src_addr(), src);
									}
								}
							}
						}
					}
				}

				if(p_header_changed) {
					/* and move payload to UDP data again */
					pbuf_header(p, -hdrs_len);
				}
			}

#endif /* SO_REUSE && SO_REUSE_RXTOALL */

			/* callback */
			if(pcb->recv != NULL) {
				/* now the recv function is responsible for freeing p */
				pcb->recv(pcb->recv_arg, pcb, p, ip_current_src_addr(), src);
			} else {
				/* no recv function registered? then we have to free the pbuf! */
				pbuf_free(p);
				goto end;
			}
		} else {
			LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: not for us.\n"));

#if LWIP_ICMP || LWIP_ICMP6

			/* No match was found, send ICMP destination port unreachable unless
			   destination address was broadcast/multicast. */
			if(!broadcast && !ip_addr_ismulticast(ip_current_dest_addr())) {
				/* move payload pointer back to ip header */
				pbuf_header_force(p, (s16_t)(ip_current_header_tot_len() + UDP_HLEN));
				icmp_port_unreach(ip_current_is_v6(), p);
			}

#endif /* LWIP_ICMP || LWIP_ICMP6 */
			UDP_STATS_INC(udp.proterr);
			UDP_STATS_INC(udp.drop);
			MIB2_STATS_INC(mib2.udpnoports);
			pbuf_free(p);
		}
	} else {
		pbuf_free(p);
	}

end:
	PERF_STOP("udp_input");
	return;
#if CHECKSUM_CHECK_UDP
chkerr:
	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
	            ("udp_input: UDP (or UDP Lite) datagram discarded due to failing checksum\n"));
	UDP_STATS_INC(udp.chkerr);
	UDP_STATS_INC(udp.drop);
	MIB2_STATS_INC(mib2.udpinerrors);
	pbuf_free(p);
	PERF_STOP("udp_input");
#endif /* CHECKSUM_CHECK_UDP */
}

/**
 * @ingroup udp_raw
 * Send data using UDP.
 *
 * @param pcb UDP PCB used to send the data.
 * @param p chain of pbuf's to be sent.
 *
 * The datagram will be sent to the current remote_ip & remote_port
 * stored in pcb. If the pcb is not bound to a port, it will
 * automatically be bound to a random port.
 *
 * @return lwIP error code.
 * - ERR_OK. Successful. No error occurred.
 * - ERR_MEM. Out of memory.
 * - ERR_RTE. Could not find route to destination address.
 * - ERR_VAL. No PCB or PCB is dual-stack
 * - More errors could be returned by lower protocol layers.
 *
 * @see udp_disconnect() udp_sendto()
 */
err_t
udp_send(struct udp_pcb* pcb, struct pbuf* p)
{
	if((pcb == NULL) || IP_IS_ANY_TYPE_VAL(pcb->remote_ip)) {
		return ERR_VAL;
	}

	/* send to the packet using remote ip and port stored in the pcb */
	return udp_sendto(pcb, p, &pcb->remote_ip, pcb->remote_port);
}

#if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
/** @ingroup udp_raw
 * Same as udp_send() but with checksum
 */
err_t
udp_send_chksum(struct udp_pcb* pcb, struct pbuf* p,
                u8_t have_chksum, u16_t chksum)
{
	if((pcb == NULL) || IP_IS_ANY_TYPE_VAL(pcb->remote_ip)) {
		return ERR_VAL;
	}

	/* send to the packet using remote ip and port stored in the pcb */
	return udp_sendto_chksum(pcb, p, &pcb->remote_ip, pcb->remote_port,
	                         have_chksum, chksum);
}
#endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */

/**
 * @ingroup udp_raw
 * Send data to a specified address using UDP.
 *
 * @param pcb UDP PCB used to send the data.
 * @param p chain of pbuf's to be sent.
 * @param dst_ip Destination IP address.
 * @param dst_port Destination UDP port.
 *
 * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
 *
 * If the PCB already has a remote address association, it will
 * be restored after the data is sent.
 *
 * @return lwIP error code (@see udp_send for possible error codes)
 *
 * @see udp_disconnect() udp_send()
 */
err_t
udp_sendto(struct udp_pcb* pcb, struct pbuf* p,
           const ip_addr_t* dst_ip, u16_t dst_port)
{
#if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
	return udp_sendto_chksum(pcb, p, dst_ip, dst_port, 0, 0);
}

/** @ingroup udp_raw
 * Same as udp_sendto(), but with checksum */
err_t
udp_sendto_chksum(struct udp_pcb* pcb, struct pbuf* p, const ip_addr_t* dst_ip,
                  u16_t dst_port, u8_t have_chksum, u16_t chksum)
{
#endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
	struct netif* netif;
	const ip_addr_t* dst_ip_route = dst_ip;

	if((pcb == NULL) || (dst_ip == NULL) || !IP_ADDR_PCB_VERSION_MATCH(pcb, dst_ip)) {
		return ERR_VAL;
	}

	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send\n"));

#if LWIP_IPV6 || (LWIP_IPV4 && LWIP_MULTICAST_TX_OPTIONS)

	if(ip_addr_ismulticast(dst_ip_route)) {
#if LWIP_IPV6

		if(IP_IS_V6(dst_ip)) {
			/* For multicast, find a netif based on source address. */
			dst_ip_route = &pcb->local_ip;
		} else
#endif /* LWIP_IPV6 */
		{
#if LWIP_IPV4 && LWIP_MULTICAST_TX_OPTIONS

			/* IPv4 does not use source-based routing by default, so we use an
			   administratively selected interface for multicast by default.
			   However, this can be overridden by setting an interface address
			   in pcb->multicast_ip that is used for routing. */
			if(!ip_addr_isany_val(pcb->multicast_ip) &&
			        !ip4_addr_cmp(ip_2_ip4(&pcb->multicast_ip), IP4_ADDR_BROADCAST)) {
				dst_ip_route = &pcb->multicast_ip;
			}

#endif /* LWIP_IPV4 && LWIP_MULTICAST_TX_OPTIONS */
		}
	}

#endif /* LWIP_IPV6 || (LWIP_IPV4 && LWIP_MULTICAST_TX_OPTIONS) */

	/* find the outgoing network interface for this packet */
	if(IP_IS_ANY_TYPE_VAL(pcb->local_ip)) {
		/* Don't call ip_route() with IP_ANY_TYPE */
		netif = ip_route(IP46_ADDR_ANY(IP_GET_TYPE(dst_ip_route)), dst_ip_route);
	} else {
		netif = ip_route(&pcb->local_ip, dst_ip_route);
	}

	/* no outgoing network interface could be found? */
	if(netif == NULL) {
		LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: No route to "));
		ip_addr_debug_print(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, dst_ip);
		LWIP_DEBUGF(UDP_DEBUG, ("\n"));
		UDP_STATS_INC(udp.rterr);
		return ERR_RTE;
	}

#if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
	return udp_sendto_if_chksum(pcb, p, dst_ip, dst_port, netif, have_chksum, chksum);
#else /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
	return udp_sendto_if(pcb, p, dst_ip, dst_port, netif);
#endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
}

/**
 * @ingroup udp_raw
 * Send data to a specified address using UDP.
 * The netif used for sending can be specified.
 *
 * This function exists mainly for DHCP, to be able to send UDP packets
 * on a netif that is still down.
 *
 * @param pcb UDP PCB used to send the data.
 * @param p chain of pbuf's to be sent.
 * @param dst_ip Destination IP address.
 * @param dst_port Destination UDP port.
 * @param netif the netif used for sending.
 *
 * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
 *
 * @return lwIP error code (@see udp_send for possible error codes)
 *
 * @see udp_disconnect() udp_send()
 */
err_t
udp_sendto_if(struct udp_pcb* pcb, struct pbuf* p,
              const ip_addr_t* dst_ip, u16_t dst_port, struct netif* netif)
{
#if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
	return udp_sendto_if_chksum(pcb, p, dst_ip, dst_port, netif, 0, 0);
}

/** Same as udp_sendto_if(), but with checksum */
err_t
udp_sendto_if_chksum(struct udp_pcb* pcb, struct pbuf* p, const ip_addr_t* dst_ip,
                     u16_t dst_port, struct netif* netif, u8_t have_chksum,
                     u16_t chksum)
{
#endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
	const ip_addr_t* src_ip;

	if((pcb == NULL) || (dst_ip == NULL) || !IP_ADDR_PCB_VERSION_MATCH(pcb, dst_ip)) {
		return ERR_VAL;
	}

	/* PCB local address is IP_ANY_ADDR? */
#if LWIP_IPV6

	if(IP_IS_V6(dst_ip)) {
		if(ip6_addr_isany(ip_2_ip6(&pcb->local_ip))) {
			src_ip = ip6_select_source_address(netif, ip_2_ip6(dst_ip));

			if(src_ip == NULL) {
				/* No suitable source address was found. */
				return ERR_RTE;
			}
		} else {
			/* use UDP PCB local IPv6 address as source address, if still valid. */
			if(netif_get_ip6_addr_match(netif, ip_2_ip6(&pcb->local_ip)) < 0) {
				/* Address isn't valid anymore. */
				return ERR_RTE;
			}

			src_ip = &pcb->local_ip;
		}
	}

#endif /* LWIP_IPV6 */
#if LWIP_IPV4 && LWIP_IPV6
	else
#endif /* LWIP_IPV4 && LWIP_IPV6 */
#if LWIP_IPV4
		if(ip4_addr_isany(ip_2_ip4(&pcb->local_ip)) ||
		        ip4_addr_ismulticast(ip_2_ip4(&pcb->local_ip))) {
			/* if the local_ip is any or multicast
			 * use the outgoing network interface IP address as source address */
			src_ip = netif_ip_addr4(netif);
		} else {
			/* check if UDP PCB local IP address is correct
			 * this could be an old address if netif->ip_addr has changed */
			if(!ip4_addr_cmp(ip_2_ip4(&(pcb->local_ip)), netif_ip4_addr(netif))) {
				/* local_ip doesn't match, drop the packet */
				return ERR_RTE;
			}

			/* use UDP PCB local IP address as source address */
			src_ip = &pcb->local_ip;
		}

#endif /* LWIP_IPV4 */
#if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
	return udp_sendto_if_src_chksum(pcb, p, dst_ip, dst_port, netif, have_chksum, chksum, src_ip);
#else /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
	return udp_sendto_if_src(pcb, p, dst_ip, dst_port, netif, src_ip);
#endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
}

/** @ingroup udp_raw
 * Same as @ref udp_sendto_if, but with source address */
err_t
udp_sendto_if_src(struct udp_pcb* pcb, struct pbuf* p,
                  const ip_addr_t* dst_ip, u16_t dst_port, struct netif* netif, const ip_addr_t* src_ip)
{
#if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
	return udp_sendto_if_src_chksum(pcb, p, dst_ip, dst_port, netif, 0, 0, src_ip);
}

/** Same as udp_sendto_if_src(), but with checksum */
err_t
udp_sendto_if_src_chksum(struct udp_pcb* pcb, struct pbuf* p, const ip_addr_t* dst_ip,
                         u16_t dst_port, struct netif* netif, u8_t have_chksum,
                         u16_t chksum, const ip_addr_t* src_ip)
{
#endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
	struct udp_hdr* udphdr;
	err_t err;
	struct pbuf* q; /* q will be sent down the stack */
	u8_t ip_proto;
	u8_t ttl;

	if((pcb == NULL) || (dst_ip == NULL) || !IP_ADDR_PCB_VERSION_MATCH(pcb, src_ip) ||
	        !IP_ADDR_PCB_VERSION_MATCH(pcb, dst_ip)) {
		return ERR_VAL;
	}

#if LWIP_IPV4 && IP_SOF_BROADCAST

	/* broadcast filter? */
	if(!ip_get_option(pcb, SOF_BROADCAST) &&
#if LWIP_IPV6
	        IP_IS_V4(dst_ip) &&
#endif /* LWIP_IPV6 */
	        ip_addr_isbroadcast(dst_ip, netif)) {
		LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
		            ("udp_sendto_if: SOF_BROADCAST not enabled on pcb %p\n", (void*)pcb));
		return ERR_VAL;
	}

#endif /* LWIP_IPV4 && IP_SOF_BROADCAST */

	/* if the PCB is not yet bound to a port, bind it here */
	if(pcb->local_port == 0) {
		LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send: not yet bound to a port, binding now\n"));
		err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);

		if(err != ERR_OK) {
			LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: forced port bind failed\n"));
			return err;
		}
	}

	/* not enough space to add an UDP header to first pbuf in given p chain? */
	if(pbuf_header(p, UDP_HLEN)) {
		/* allocate header in a separate new pbuf */
		q = pbuf_alloc(PBUF_IP, UDP_HLEN, PBUF_RAM);

		/* new header pbuf could not be allocated? */
		if(q == NULL) {
			LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: could not allocate header\n"));
			return ERR_MEM;
		}

		if(p->tot_len != 0) {
			/* chain header q in front of given pbuf p (only if p contains data) */
			pbuf_chain(q, p);
		}

		/* first pbuf q points to header pbuf */
		LWIP_DEBUGF(UDP_DEBUG,
		            ("udp_send: added header pbuf %p before given pbuf %p\n", (void*)q, (void*)p));
	} else {
		/* adding space for header within p succeeded */
		/* first pbuf q equals given pbuf */
		q = p;
		LWIP_DEBUGF(UDP_DEBUG, ("udp_send: added header in given pbuf %p\n", (void*)p));
	}

	LWIP_ASSERT("check that first pbuf can hold struct udp_hdr",
	            (q->len >= sizeof(struct udp_hdr)));
	/* q now represents the packet to be sent */
	udphdr = (struct udp_hdr*)q->payload;
	udphdr->src = lwip_htons(pcb->local_port);
	udphdr->dest = lwip_htons(dst_port);
	/* in UDP, 0 checksum means 'no checksum' */
	udphdr->chksum = 0x0000;

	/* Multicast Loop? */
#if (LWIP_IPV4 && LWIP_MULTICAST_TX_OPTIONS) || (LWIP_IPV6 && LWIP_IPV6_MLD)

	if(((pcb->flags & UDP_FLAGS_MULTICAST_LOOP) != 0) && ip_addr_ismulticast(dst_ip)) {
		q->flags |= PBUF_FLAG_MCASTLOOP;
	}

#endif /* (LWIP_IPV4 && LWIP_MULTICAST_TX_OPTIONS) || (LWIP_IPV6 && LWIP_IPV6_MLD) */

	LWIP_DEBUGF(UDP_DEBUG, ("udp_send: sending datagram of length %"U16_F"\n", q->tot_len));

#if LWIP_UDPLITE

	/* UDP Lite protocol? */
	if(pcb->flags & UDP_FLAGS_UDPLITE) {
		u16_t chklen, chklen_hdr;
		LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE packet length %"U16_F"\n", q->tot_len));
		/* set UDP message length in UDP header */
		chklen_hdr = chklen = pcb->chksum_len_tx;

		if((chklen < sizeof(struct udp_hdr)) || (chklen > q->tot_len)) {
			if(chklen != 0) {
				LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE pcb->chksum_len is illegal: %"U16_F"\n", chklen));
			}

			/* For UDP-Lite, checksum length of 0 means checksum
			   over the complete packet. (See RFC 3828 chap. 3.1)
			   At least the UDP-Lite header must be covered by the
			   checksum, therefore, if chksum_len has an illegal
			   value, we generate the checksum over the complete
			   packet to be safe. */
			chklen_hdr = 0;
			chklen = q->tot_len;
		}

		udphdr->len = lwip_htons(chklen_hdr);
		/* calculate checksum */
#if CHECKSUM_GEN_UDP
		IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_UDP) {
#if LWIP_CHECKSUM_ON_COPY

			if(have_chksum) {
				chklen = UDP_HLEN;
			}

#endif /* LWIP_CHECKSUM_ON_COPY */
			udphdr->chksum = ip_chksum_pseudo_partial(q, IP_PROTO_UDPLITE,
			                 q->tot_len, chklen, src_ip, dst_ip);
#if LWIP_CHECKSUM_ON_COPY

			if(have_chksum) {
				u32_t acc;
				acc = udphdr->chksum + (u16_t)~(chksum);
				udphdr->chksum = FOLD_U32T(acc);
			}

#endif /* LWIP_CHECKSUM_ON_COPY */

			/* chksum zero must become 0xffff, as zero means 'no checksum' */
			if(udphdr->chksum == 0x0000) {
				udphdr->chksum = 0xffff;
			}
		}
#endif /* CHECKSUM_GEN_UDP */

		ip_proto = IP_PROTO_UDPLITE;
	} else
#endif /* LWIP_UDPLITE */
	{      /* UDP */
		LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP packet length %"U16_F"\n", q->tot_len));
		udphdr->len = lwip_htons(q->tot_len);
		/* calculate checksum */
#if CHECKSUM_GEN_UDP
		IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_UDP) {
			/* Checksum is mandatory over IPv6. */
			if(IP_IS_V6(dst_ip) || (pcb->flags & UDP_FLAGS_NOCHKSUM) == 0) {
				u16_t udpchksum;
#if LWIP_CHECKSUM_ON_COPY

				if(have_chksum) {
					u32_t acc;
					udpchksum = ip_chksum_pseudo_partial(q, IP_PROTO_UDP,
					                                     q->tot_len, UDP_HLEN, src_ip, dst_ip);
					acc = udpchksum + (u16_t)~(chksum);
					udpchksum = FOLD_U32T(acc);
				} else
#endif /* LWIP_CHECKSUM_ON_COPY */
				{
					udpchksum = ip_chksum_pseudo(q, IP_PROTO_UDP, q->tot_len,
					                             src_ip, dst_ip);
				}

				/* chksum zero must become 0xffff, as zero means 'no checksum' */
				if(udpchksum == 0x0000) {
					udpchksum = 0xffff;
				}

				udphdr->chksum = udpchksum;
			}
		}
#endif /* CHECKSUM_GEN_UDP */
		ip_proto = IP_PROTO_UDP;
	}

	/* Determine TTL to use */
#if LWIP_MULTICAST_TX_OPTIONS
	ttl = (ip_addr_ismulticast(dst_ip) ? udp_get_multicast_ttl(pcb) : pcb->ttl);
#else /* LWIP_MULTICAST_TX_OPTIONS */
	ttl = pcb->ttl;
#endif /* LWIP_MULTICAST_TX_OPTIONS */

	LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04"X16_F"\n", udphdr->chksum));
	LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,0x%02"X16_F",)\n", (u16_t)ip_proto));
	/* output to IP */
	NETIF_SET_HWADDRHINT(netif, &(pcb->addr_hint));
	err = ip_output_if_src(q, src_ip, dst_ip, ttl, pcb->tos, ip_proto, netif);
	NETIF_SET_HWADDRHINT(netif, NULL);

	/* @todo: must this be increased even if error occurred? */
	MIB2_STATS_INC(mib2.udpoutdatagrams);

	/* did we chain a separate header pbuf earlier? */
	if(q != p) {
		/* free the header pbuf */
		pbuf_free(q);
		q = NULL;
		/* p is still referenced by the caller, and will live on */
	}

	UDP_STATS_INC(udp.xmit);
	return err;
}

/**
 * @ingroup udp_raw
 * Bind an UDP PCB.
 *
 * @param pcb UDP PCB to be bound with a local address ipaddr and port.
 * @param ipaddr local IP address to bind with. Use IP4_ADDR_ANY to
 * bind to all local interfaces.
 * @param port local UDP port to bind with. Use 0 to automatically bind
 * to a random port between UDP_LOCAL_PORT_RANGE_START and
 * UDP_LOCAL_PORT_RANGE_END.
 *
 * ipaddr & port are expected to be in the same byte order as in the pcb.
 *
 * @return lwIP error code.
 * - ERR_OK. Successful. No error occurred.
 * - ERR_USE. The specified ipaddr and port are already bound to by
 * another UDP PCB.
 *
 * @see udp_disconnect()
 */
err_t
udp_bind(struct udp_pcb* pcb, const ip_addr_t* ipaddr, u16_t port)
{
	struct udp_pcb* ipcb;
	u8_t rebind;

#if LWIP_IPV4

	/* Don't propagate NULL pointer (IPv4 ANY) to subsequent functions */
	if(ipaddr == NULL) {
		ipaddr = IP4_ADDR_ANY;
	}

#endif /* LWIP_IPV4 */

	/* still need to check for ipaddr == NULL in IPv6 only case */
	if((pcb == NULL) || (ipaddr == NULL)) {
		return ERR_VAL;
	}

	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_bind(ipaddr = "));
	ip_addr_debug_print(UDP_DEBUG | LWIP_DBG_TRACE, ipaddr);
	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, (", port = %"U16_F")\n", port));

	rebind = 0;

	/* Check for double bind and rebind of the same pcb */
	for(ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
		/* is this UDP PCB already on active list? */
		if(pcb == ipcb) {
			rebind = 1;
			break;
		}
	}

	/* no port specified? */
	if(port == 0) {
		port = udp_new_port();

		if(port == 0) {
			/* no more ports available in local range */
			LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: out of free UDP ports\n"));
			return ERR_USE;
		}
	} else {
		for(ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
			if(pcb != ipcb) {
				/* By default, we don't allow to bind to a port that any other udp
				   PCB is already bound to, unless *all* PCBs with that port have tha
				   REUSEADDR flag set. */
#if SO_REUSE
				if(!ip_get_option(pcb, SOF_REUSEADDR) ||
				        !ip_get_option(ipcb, SOF_REUSEADDR))
#endif /* SO_REUSE */
				{
					/* port matches that of PCB in list and REUSEADDR not set -> reject */
					if((ipcb->local_port == port) &&
					        /* IP address matches? */
					        ip_addr_cmp(&ipcb->local_ip, ipaddr)) {
						/* other PCB already binds to this local IP and port */
						LWIP_DEBUGF(UDP_DEBUG,
						            ("udp_bind: local port %"U16_F" already bound by another pcb\n", port));
						return ERR_USE;
					}
				}
			}
		}
	}

	ip_addr_set_ipaddr(&pcb->local_ip, ipaddr);

	pcb->local_port = port;
	mib2_udp_bind(pcb);

	/* pcb not active yet? */
	if(rebind == 0) {
		/* place the PCB on the active list if not already there */
		pcb->next = udp_pcbs;
		udp_pcbs = pcb;
	}

	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("udp_bind: bound to "));
	ip_addr_debug_print(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, &pcb->local_ip);
	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, (", port %"U16_F")\n", pcb->local_port));
	return ERR_OK;
}

/**
 * @ingroup udp_raw
 * Connect an UDP PCB.
 *
 * This will associate the UDP PCB with the remote address.
 *
 * @param pcb UDP PCB to be connected with remote address ipaddr and port.
 * @param ipaddr remote IP address to connect with.
 * @param port remote UDP port to connect with.
 *
 * @return lwIP error code
 *
 * ipaddr & port are expected to be in the same byte order as in the pcb.
 *
 * The udp pcb is bound to a random local port if not already bound.
 *
 * @see udp_disconnect()
 */
err_t
udp_connect(struct udp_pcb* pcb, const ip_addr_t* ipaddr, u16_t port)
{
	struct udp_pcb* ipcb;

	if((pcb == NULL) || (ipaddr == NULL)) {
		return ERR_VAL;
	}

	if(pcb->local_port == 0) {
		err_t err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);

		if(err != ERR_OK) {
			return err;
		}
	}

	ip_addr_set_ipaddr(&pcb->remote_ip, ipaddr);
	pcb->remote_port = port;
	pcb->flags |= UDP_FLAGS_CONNECTED;

	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("udp_connect: connected to "));
	ip_addr_debug_print(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
	                    &pcb->remote_ip);
	LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, (", port %"U16_F")\n", pcb->remote_port));

	/* Insert UDP PCB into the list of active UDP PCBs. */
	for(ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
		if(pcb == ipcb) {
			/* already on the list, just return */
			return ERR_OK;
		}
	}

	/* PCB not yet on the list, add PCB now */
	pcb->next = udp_pcbs;
	udp_pcbs = pcb;
	return ERR_OK;
}

/**
 * @ingroup udp_raw
 * Disconnect a UDP PCB
 *
 * @param pcb the udp pcb to disconnect.
 */
void
udp_disconnect(struct udp_pcb* pcb)
{
	/* reset remote address association */
#if LWIP_IPV4 && LWIP_IPV6
	if(IP_IS_ANY_TYPE_VAL(pcb->local_ip)) {
		ip_addr_copy(pcb->remote_ip, *IP_ANY_TYPE);
	} else {
#endif
		ip_addr_set_any(IP_IS_V6_VAL(pcb->remote_ip), &pcb->remote_ip);
#if LWIP_IPV4 && LWIP_IPV6
	}

#endif
	pcb->remote_port = 0;
	/* mark PCB as unconnected */
	pcb->flags &= ~UDP_FLAGS_CONNECTED;
}

/**
 * @ingroup udp_raw
 * Set a receive callback for a UDP PCB
 *
 * This callback will be called when receiving a datagram for the pcb.
 *
 * @param pcb the pcb for which to set the recv callback
 * @param recv function pointer of the callback function
 * @param recv_arg additional argument to pass to the callback function
 */
void
udp_recv(struct udp_pcb* pcb, udp_recv_fn recv, void* recv_arg)
{
	/* remember recv() callback and user data */
	pcb->recv = recv;
	pcb->recv_arg = recv_arg;
}

/**
 * @ingroup udp_raw
 * Remove an UDP PCB.
 *
 * @param pcb UDP PCB to be removed. The PCB is removed from the list of
 * UDP PCB's and the data structure is freed from memory.
 *
 * @see udp_new()
 */
void
udp_remove(struct udp_pcb* pcb)
{
	struct udp_pcb* pcb2;

	mib2_udp_unbind(pcb);

	/* pcb to be removed is first in list? */
	if(udp_pcbs == pcb) {
		/* make list start at 2nd pcb */
		udp_pcbs = udp_pcbs->next;
		/* pcb not 1st in list */
	} else {
		for(pcb2 = udp_pcbs; pcb2 != NULL; pcb2 = pcb2->next) {
			/* find pcb in udp_pcbs list */
			if(pcb2->next != NULL && pcb2->next == pcb) {
				/* remove pcb from list */
				pcb2->next = pcb->next;
				break;
			}
		}
	}

	memp_free(MEMP_UDP_PCB, pcb);
}

/**
 * @ingroup udp_raw
 * Create a UDP PCB.
 *
 * @return The UDP PCB which was created. NULL if the PCB data structure
 * could not be allocated.
 *
 * @see udp_remove()
 */
struct udp_pcb*
udp_new(void)
{
	struct udp_pcb* pcb;
	pcb = (struct udp_pcb*)memp_malloc(MEMP_UDP_PCB);

	/* could allocate UDP PCB? */
	if(pcb != NULL) {
		/* UDP Lite: by initializing to all zeroes, chksum_len is set to 0
		 * which means checksum is generated over the whole datagram per default
		 * (recommended as default by RFC 3828). */
		/* initialize PCB to all zeroes */
		memset(pcb, 0, sizeof(struct udp_pcb));
		pcb->ttl = UDP_TTL;
#if LWIP_MULTICAST_TX_OPTIONS
		udp_set_multicast_ttl(pcb, UDP_TTL);
#endif /* LWIP_MULTICAST_TX_OPTIONS */
	}

	return pcb;
}

/**
 * @ingroup udp_raw
 * Create a UDP PCB for specific IP type.
 *
 * @param type IP address type, see @ref lwip_ip_addr_type definitions.
 * If you want to listen to IPv4 and IPv6 (dual-stack) packets,
 * supply @ref IPADDR_TYPE_ANY as argument and bind to @ref IP_ANY_TYPE.
 * @return The UDP PCB which was created. NULL if the PCB data structure
 * could not be allocated.
 *
 * @see udp_remove()
 */
struct udp_pcb*
udp_new_ip_type(u8_t type)
{
	struct udp_pcb* pcb;
	pcb = udp_new();
#if LWIP_IPV4 && LWIP_IPV6

	if(pcb != NULL) {
		IP_SET_TYPE_VAL(pcb->local_ip,  type);
		IP_SET_TYPE_VAL(pcb->remote_ip, type);
	}

#else
	LWIP_UNUSED_ARG(type);
#endif /* LWIP_IPV4 && LWIP_IPV6 */
	return pcb;
}

/** This function is called from netif.c when address is changed
 *
 * @param old_addr IP address of the netif before change
 * @param new_addr IP address of the netif after change
 */
void udp_netif_ip_addr_changed(const ip_addr_t* old_addr, const ip_addr_t* new_addr)
{
	struct udp_pcb* upcb;

	if(!ip_addr_isany(old_addr) && !ip_addr_isany(new_addr)) {
		for(upcb = udp_pcbs; upcb != NULL; upcb = upcb->next) {
			/* PCB bound to current local interface address? */
			if(ip_addr_cmp(&upcb->local_ip, old_addr)) {
				/* The PCB is bound to the old ipaddr and
				 * is set to bound to the new one instead */
				ip_addr_copy(upcb->local_ip, *new_addr);
			}
		}
	}
}

#if UDP_DEBUG
/**
 * Print UDP header information for debug purposes.
 *
 * @param udphdr pointer to the udp header in memory.
 */
void
udp_debug_print(struct udp_hdr* udphdr)
{
	LWIP_DEBUGF(UDP_DEBUG, ("UDP header:\n"));
	LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
	LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     %5"U16_F"     | (src port, dest port)\n",
	                        lwip_ntohs(udphdr->src), lwip_ntohs(udphdr->dest)));
	LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
	LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     0x%04"X16_F"    | (len, chksum)\n",
	                        lwip_ntohs(udphdr->len), lwip_ntohs(udphdr->chksum)));
	LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
}
#endif /* UDP_DEBUG */

#endif /* LWIP_UDP */
